1. Field of the Invention
The present invention relates generally to windshield wipers and, more specifically, to the squeegee elements employed in windshield wiper blades.
2. Description of the Prior Art
The problems attendant to appropriate design of squeegee elements for windshield wipers are well known to those skilled in the art. Among the chief problems encountered are excessive noise, particularly during the reversing operation of the blades, freezing of the squeegee element to the window surface it is intended to wipe clear during inclement weather, permanent setting of elastomeric squeegees in one direction, and lack of consistency in friction and wipe quality characteristics of the squeegee elements. As an overriding concern, since these elements are frequently replaced by operators of motor vehicles, it is necessary that an economically manufacturable configuration be established for the squeegee element.
In the prior art, attempts have been made to reduce noise together with a tendency to permanent set of elastomeric squeegies through providing configurations which enhance the resiliency of the squeegee element. Exemplary of the prior art are U.S. Pat. Nos. 3,566,432 and 3,785,002 to Quinlan et al., and U.S. Pat. No. 3,428,997 to Rickett, as well as that element disclosed in U.S. Pat. No. 3,879,794 to Roberts, Jr. While the squeegee elements shown in these patents, as well as others available commercially, have had some success in improving resilience of the squeegee elements, it can be seen that they often involve the manufacture of rather complicated and expensive shapes and it has been determined that further improvements in noise reduction in the operation of the elements is desirable. Improvements are also desired in the area of resistance to permanent set and to freezing in inclement weather conditions, a problem which is particularly acute in those prior art elements which employ elongated external slots to increase element flexibility.